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Solution_Homework 3 - 2011(1)

# Solution_Homework 3 - 2011(1) - correction is needed The...

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The University of Missouri-Columbia Department of Civil Engineering Assigned: Monday, September 12, 2011 Due: Friday, September 16, 2011 CE 3400 – Fall 2011 SOLUTION Homework No. 3 – Site Investigation 1. An SPT measurement is made at a depth of 20 ft below the ground surface. The recorded blow counts or successive 6 in penetrations are 7-12-11. Assume this measurement was made using equipment with 60% efficiency. a. What is the N 60 value at this depth? N value is the sum of the number of blows over the last 12 inches 23 11 12 60 N b. If the effective stress at this depth is 1200 psf, what is the value of N 1,60 ? (see pg 93 to 95 of Coduto) N 1,60 is the blow count corrected for hammer efficiency and for overburden stress. In this case the hammer efficiency is at 60% so no

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Unformatted text preview: correction is needed. The overburden correction is: 41 1200 2000 60 60 , 1 psf psf N N 2. A Shelby tube for sampling has an outside diameter of 3 inches and a wall thickness of 1/16 in. Compute the area ratio of the sampler. Area ratio is the ratio of the annular cross-sectional area of the sampler tube to the circular cross sectional area of the sampler itself. Area ratios of less than about 15% are needed for undisturbed samples: % 8 . 8 4918 . 6 4918 . 6 068 . 7 ) 16 1 5 . 1 ( ) 16 1 5 . 1 ( ) 5 . 1 ( 2 2 2 2 2 2 r r r A I R 3. Work Problem 3.7 in Coduto 4. Work Problem 3.9 in Coduto 5. Work Problem 3.26 in Coduto...
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Solution_Homework 3 - 2011(1) - correction is needed The...

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